For subsea applications, (e.g., subsea oil production, subsea energy transmission, or subsea telecommunications), equipment to be operated subsea is configured for this harsh environment. A major obstacle in deep water is the extreme high pressure experienced by the equipment at these water depths. Accordingly, pressure-resistant vessels, so-called pressure canisters, may be used to protect the equipment at these depths from the high pressure by providing an inside pressure of approximately one atmosphere (which corresponds with approximately to 100,000 Pascal or 1 bar).
The pressure canisters used subsea to maintain and simulate an ambient pressure similar to what is experienced at the surface are also called one-atmosphere chambers, one-atmosphere vessels, or one-atmosphere canisters. A common use, for example, in the oil industry for such canisters is to protect pressure-sensitive components subsea. The pressure canisters may be operated in a depth of approximately 3,000 meters below the surface. Therefore, the pressure outside the canister may become extremely large, for example as high as 300 bar (3 million Pascal). Therefore, a high resistive sealing is required at every opening of the canister.
It may be required to fill the pressure canister with a certain gas or fluid. For example, in case the pressure canister contains electrical components, it may be required to fill the pressure canister with sulfur hexafluoride (SF6) due to its dielectric properties. However, according to the Intergovernmental Penal on Climate Change, SF6 is the most potent greenhouse gas and authorities very concerned for waste to the atmosphere. Therefore, a waste of SF6 to the atmosphere shall be avoided, particularly during filling or removing the gas into or from the pressure canister.
Therefore, there is a need for a valve for a subsea pressure canister that offers a high degree of safety in operation and during filling and evacuation of a fluid or gas, especially SF6 gas.